Apparatus for the cutting of a yarn travelling in a tube by means of a fluid

ABSTRACT

The present invention relates to a process and a device for the cutting of a yarn travelling in a tube by means of a fluid under pressure. According to the process, the yarn is forced against the cutting edge of a cutting obstacle, the cutting being effected by the pressure of the yarn upon the obstacle, which is created by the pulling force of the fluid. The device is composed of a sleeve which may be connected respectively to the upper and lower extremity of two tubes defining the path of the yarn and inside of which is placed a cutting blade, which is transversely movable, the blade being affixed in an aperture provided in a sliding piston which may move in a bore, the axis of the bore being perpendicular to the path of the yarn. The blade may be pivoting. A retractable plunger may be located in the extension of the upper tube to modify the course of the yarn at least at the moment of the cutting. The present invention may be applied to the cutting of all types of yarns.

Hautemont et al.

[ APPARATUS FOR THE CUTTING OF A YARN TRAVELLING IN A TUBE BY MEANS OF A FLUID [75] Inventors: Jean-Claude Hautemont,

Gif-sur-Yvette; Rolland Sartopi, Roanne, both of France [73] Assignee: Rhone-Poulenc-Textile, Paris,

France [22] Filed: Dec. 13, 1974 [21] Appl. No.2 532,615

Related US. Application Data [62] Division of Ser. No. 476,276, June 4, 1974, Pat. No. 3,864,998, which is a division of Ser. No. 375,068, June 29, 1973, abandoned.

[52] US. Cl. 83/100; 83/177; 83/402 [51] Int. Cl. B26D 5/04; B26D 7/06 [58] Field of Search 83/402, 100, 578,53,177, 83/22, 24, 53; 225/93, 103, l, 4

[56] References Cited UNITED STATES PATENTS 2,888,075 5/1959 Davidson 83/578 X 3,241,234 3/1966 Kiefer et al. 83/100 X 3,285,114 11/1966 Johnson, .lr.. 83/402 3,683,732 8/1972 Juppet 83/402 X Dec. 2, 1975 Primary E.\'aminerFrank T. Yost Attorney, Agent, or FirmSherman & Shalloway [57] ABSTRACT The present invention relates to a process and a device for the cutting of a yarn travelling in a tube by means of a fluid under pressure.

According to the process, the yarn is forced against the cutting edge of a cutting obstacle, the cutting being effected by the pressure of the yarn upon the obstacle, which is created by the pulling force of the fluid.

The blade may be pivoting. A retractable plunger may be located in the extension of the upper tube to modify the course of the yarn at least at the moment of the cutting.

The present invention may be applied to the cutting of all types of yarns.

8 Claims, 9 Drawing Figures US. Patent Dec. 2, 1975 Sheet 1 0133 a j FIG.3

US. Patent Dec. 2, 1975 Sheet 2 0f 3 FIGJS US. Patent Dec. 2, 1975 Sheet 3 of3 3,922,938

.Illllii O I Ii 18 APPARATUS FOR THE CUTTING OF A YARN TRAVELLING IN A TUBE BY MEANS OF A FLUID This is a division of application Ser. No. 476,276, filed June 4, 1974, now U.S. Pat. No. 3,864,998, which is itself a divisional of application Ser. No. 375,068, filed June 29, 1973, now abandoned.

The present invention concerns a process and apparatus for cutting a moving yarn.

It relates more particularly to a process and apparatus for cutting a yarn travelling in a tube by means of a fluid under pressure.

The method of continuously transporting a yarn in a tube by means of a fluid under pressure such as compressed air is becoming increasingly common in the textile industry. This type of transport is shown, for example, in French patent application No. 72/ 19405, filed by one of the applicants of the present invention.

That application relates to a device for the transport of at least one yarn from a delivery point toward several receiving means. It comprises a delivery tube and several distribution tubes connected to the delivery tube, fed alternately by means of a fluid under pressure and travelled alternately by the yarn. The passage from one of the distribution tubes to the other requires the cutting of the yarn in the delivery tube ahead of the inlet of each of the distribution tubes. Thus, it is necessary to provide a suitable yarn cutter.

Numerous models of yarn cutters are known. Certain cutters are based on the principle of a cutting by-shearing or scissoring between two closing blades (scissors), or between a fixed blade and a movable blade. Other types are based on the principle of percussion, with a movable blade hitting the yarn on a fixed plate.

It is also known to cut the yarns by causing either their melting (synthetic yarns) or their combustion (artificial yarns).

None of these yarn cutters is particularly adapted for the cutting of a yarn being air transported in a tube, particularly at high speeds, as is the case, for example, in the patent application mentioned above.

Mechanical devices offer the disadvantage that they cause the blocking of the yarn at the time of the cutting. This blocking up causes the yarn to accumulate, with the greater the speed, the greater the accumulation, thus creating a risk of snags.

The devices which cut the yarn by melting or burning it are difficult to use under such transporting conditions.

Moreover, during its operation, the yarn cutter should perturb to a minimum the flow of the fluid.

It is, therefore, an object of the present invention to provide a process and apparatus for cutting yarn transported continuously at high speeds by fluid under pressure through a conduit which avoids the above noted disadvantages.

It is an additional object of the present invention to provide a process for cutting travelling yarn by contacting the travelling yarn with cutting means including a cutting blade which crosses the direction of travel of the yarn.

An additional object of the present invention is to provide a process whereby the cutting means for contacting the travelling yarn is located in the vicinity of the travelling yarn and is adapted to move transversely across the path of the travelling yarn to contact the yarn.

An additional object of the present invention is to provide a process for cutting travelling yarns wherein the cutting means in addition to its transverse movement across the path of the yarn is adapted to pivot about an axis perpendicular to the path of the yarn to reduce the cutting angle of the yarn as it is being cut by the cutting means.

A further object of the present invention is to provide apparatus for cutting yarn transported continuously at high speeds by fluid under pressure through a conduit which includes a sleeve having a central opening through which the yarn passes and a transverse opening through which cutting means are transversely movable with respect to the path of the yarn and which is capable of moving between two positions located on either side of the normal path of the yarn.

A still further object of the present invention is to provide cutting apparatus in which the cutting means has a small cross-section with respect to the crosssection of the conduit through which the yarn is travelling so that there is a minimum of interference of the flow of air through the conduit.

Yet, a further object of the present invention is to provide cutting apparatus in which the cutting means is carried in an aperture in a sliding piston which moves transversely through a bore in a sleeve connected to the conduit through which the yarn travels.

A still further object of the present invention is to provide means to pivot the cutting blade as it moves transversely past the normal path of the yarn.

An additional object of the present invention is to provide a retractible plunger in the conduit through which the travelling yarn is moving which will contact the yarn after it is contacted by the cutting means to further reduce the cutting angle of the yarn.

Other objects and advantages of the present invention will become apparent from a description of the preferred embodiments taken in conjunction with the accompanying drawings.

According to the present invention, these and related objects are accomplished economically and conveniently by providing a process for cutting a yarn travelling continuously through a conduit by means of a fluid under pressure in which the yarn is contacted by the cutting blade of a cutting obstacle located in the vicinity of the path of the yarn and oriented towards the upstream portion of the yarn delivery tube, the yarn being cut by the pressure that it exerts upon the cutting blade created by the pulling force of the fluid.

According to an advantageous method of carrying out the present invention, the cutting obstacle is moved transversely with respect to the path of the yarn so as to meet the yarn and cause its deviation and slowing down in such a manner that, with the yarn retaining its initial feeding speed, it is forced against the cutting blade of the cutting obstacle. In the process according to the present invention, the pulling force of the fluid under pressure is used as. the energy to cause the cutting.

According to another aspect of the present invention, apparatus for cutting yarn travelling through a conduit is described in which the conduit is defined by a yarn delivery tube and a yarn exit tube axially connected in the central opening of a sleeve which also has a transverse opening inside of which a cutting means is movable transversely with respect to the path of the yarn and in which the cutting blade of the cutting means is contained in a plane parallel to that of the yarn path, the cutting means and cutting blade adapted for movement to extreme positions located on either side of the normal path of the yarn.

Preferably, the cutting means has an elongated crosssection, which is small with respect to the cross-section of the tubes, so as to disturb only to a minimum the flow of the air through the tubes during the movement of the cutting means.

The cutting means is advantageously composed of a cutting blade, substantially parallel to the normal path of the yarn in the tube and moving in a reversible translation motion in a direction substantially perpendicular to the path of the yarn between two points on either side of the yarn path.

The apparatus of the present invention isperfectly suitable for cutting yarn travelling inside a tube by means of a fluid. In particular, it is well adapted to cut a yarn travelling at high speeds. By high speeds is meant speeds higher than 3,000 m./min. and which may reach up to 6,000 to 7,000 m./min. and higher.

According to one embodiment of the present invention, the yarn cutting apparatus, or yarn cutter, includes a sleeve having a central opening which holds the lower extremity of a yarn delivery tube and the upper extremity of a yarn exit tube in axial alignment; a transverse opening extends through the sleeve between the extremities of the two tubes. Sliding means, such as a piston, is adapted to slide within the transverse opening of the sleeve; the cutting means is carried within an opening which extends transversely through the sliding means. As the sliding means moves through the transverse opening, the cutting means is carried past the path of the travelling yarn to bring the cutting blade into contact with the yarn to deviate it from its normal path and to effect the cutting thereof by the force of the fluid pressure on the yarn.

According to a further aspect of the present invention, the cutting blade may pivot about an axis located both in a plane substantially orthoganol to the axis of the sleeve and in a plane substantially orthoganol to the axis of the transverse opening of the sleeve, the direction of the pivoting movement being the same as the direction of the movement of the slide means. The pivoting of the cutting blade and the additional movement of the cutting edge thereof result in a safer and cleaner cutting and improvement of the performance of the apparatus by reducing the cutting angle of the yarn and by placing the cutting blade closer to the bisectrix of the cutting angle.

The cutting angle refers to the angle formed by the two ends of yarn located immediately above and immediately below the cutting blade when the cutting means has reached one of the two extreme positions of its movement.

According to a second embodiment of the present invention, a retractible plunger is located in the central opening of the sleeve and is capable of moving in the direction of the transverse opening at the time of the cutting so as to meet the upper yarn end and cause its deviation, which leads to a reduction of the cutting angle. According to a preferred embodiment, the retractible plunger includes a sliding tubular piece which extends the yam deliverytube. It is also possible to have a retractible plunger which extends the yarn exit tube.

According to a preferred embodiment of the present invention, the yarn cutter includes the retractible plunger in addition to the means for pivoting the cutting blade.

The present invention will be better understood with the aid of the attached figures and following example which are given for purposes of illustration only.

FIGS. 1, 2 and 3 are elevational sectional views of one embodiment of the yarn cutter according to the present invention in its various operating stages.

FIG. 4 is a top view of the sliding piston of the yarn cutter as shown in FIGS. 1, 2 and 3.

FIG. 5 is a diagrammatic, elevational, sectional view of a yarn cutter according to the present invention with a pivoting blade.

FIG. 6 is a sectional side view showing the construc tion details of a yarn cutter with a pivoting cutting blade according to the present invention.

FIG. 7 is a partial elevational view of the yarn cutter of FIG. 6 showing, more particularly, the device controlling the pivoting of the blade.

FIG. 8 shows a yarn cutter according to the present invention with a retractible plunger.

FIG. 9 shows a yarn cutter according to the present invention with a pivoting blade and a retractible plunger.

The yarn cutting apparatus includes a conduit 10 through which yarn 16, coming, for example, from a spinning means (not shown), is transported by means of a flow of air circulating at high speed. The conduit includes a yarn delivery tube 12 and a yarn exit tube 14. The end portions of tubes 12 and 14 are held in axial alignment in the upper portion 13 and lower portion 15, respectively, of the cylindrical central opening 20 of sleeve member 18. A transverse opening, such as cylindrical bore 22, extends through sleeve 18 between the upper and lower portions thereof and is essentially perpendicular to the central opening 20. The upper portion 13 of the central opening 20 ends in a narrowed portion 24 which opens into bore 22 through an aperture 26, the diameter of which is smaller than that of the central opening. The lower portion 15 of the central opening has a widened portion 28 which opens into bore 22 through an aperture 30, the diameter of which is greater than that of the central opening.

In bore 22, slide means, such as cylindrical piston 32,

may move alternately from left to right and from rightto left; FIGS. 2 and 3 show it at the end of its movement, on the right. The control for this movement (not shown), may be pneumatic, mechanical, electromagnetic, etc.

The piston 32 as seen in FIG. 4 has a lateral opening, such as aperture 34 which has an elongated shape and is rounded at its ends and can be obtained by machining or molding. The width 36 of aperture 34 is greater than the diameter of aperture 26, but less than that of aperture 30, so as to avoid any possible snagging of yarn 16 passing through aperture 34. The cutting means 42 includes the partition or base 38 and cutting blade 40 which is housed in the aperture 34 of piston 32, and divides the latter into two approximately equal portions; the cutting blade and the partition are mounted to be substantially parallel to the normal path of the yarn 16 through conduit 10. The normal path of the yarn is approximately the same as the axis of conduit 10.

The operation of the yarn cutter is as follows:

With the piston 32 in the position of FIG. 1, yarn 16, under the impulse of the flow of air in the conduit, travels through the conduit including tubes 12 and 14 and lateral opening 34 of piston 32 in bore 22, without substantially deviating from its normal path which, as noted, approximates the axis of the conduit 10. To cause the cutting of the yarn, piston 32 is moved by any suitable driving means from left to right as seen in FIG. 1 until it reaches the position shown in FIG. 2. During this transverse movement of the piston 32, partition 38 and blade 40 are brought into contact with and move the travelling yarn as the cutting means crosses the normal path of the yarn. The friction thus caused upon the yarn l6 slows down its travelling speed and a double loop is formed on the upper portion of the yarn which places yarn 16 in a straddling position on the cutting edge of blade 40. This double loop is visible in FIG. 3 in which it has been illustrated as greatly enlarged for a better understanding of the drawing. Since the air acts in the same direction upon the ends A, B and C of the double loop, the yarn exerts a pressure upon the blade and, with the help of the turbulence in the conduit, it is cut immediately. Since the flow of air continues to act on the yarn, the yarn continues to flow through the conduit and to regain its normal path; as the direction of the movement of the sliding piston reverses from its extreme right position to its extreme left position, the cutting process is repeated. Preferably, the arrangement of the piston 32 in the transverse cylindrical bore 22 is such that the travel of the piston between its extreme left and right positions is such that the cutting obstacle does not obstruct the flow of air through the conduit when in its extreme left and right positions, i.e. the distance travelled by the cutting means should be at least as great as the diameter of the conduit with the center of the movement coinciding with the axis of the conduit. The thickness of the partition and cutting blade should be as thin as possible to minimize the obstruction of flow of air through the conduit as the cutting means passes through the conduit.

FIG. 5 shows a yarn cutter identical to that of FIGS. 1, 2 and 3 except that the cutting blade may pivot around an axis 44 which is perpendicular to the axis of bore 22. It can be seen that the cutting angle, alpha, will be less than 90, while it is about 120 in FIG. 2; this reduced angle facilitates the cutting action of the cutting blade.

One form of pivoting means to pivotally rotate the cutting blade in the direction of and during the transverse movement of the cutting means about a pivot axis which is perpendicular to the axis of the sleeve and to the axis of the transverse bore of the sleeve is shown in FIGS. 6 and 7.

The cutting blade and partition are integrally connected with a support 46 which includes two journals 47 and 48 housed in a bore 49 made transversely in the sliding piston 32. Advantageously, journals 47 and 48 are extended exteriorly of piston 32 and are housed partially into elongated apertures 50 provided in the body of sleeve 18. The axis of the journals coincide with the pivot axis 55. This type of assembly also enables the blade support 46 to prevent piston 32 from rotating about its own axis.

The pivoting of the blade support 46 during the transverse movement of the piston 32 is assured by a small rod or link 51 hinged around an axle 52 which is fixedly mounted to the body of sleeve 18. Small rod 51 has a groove 53 in which the flat end of a crank-pin 54 of the blade support 46 may slide. Thus, blade support 46,

which is housed in the sliding piston 32, moves with the latter by sliding in the elongated apertures 50. The sliding movement of the journals in the elongated apertures in sleeve 18 causes the rod 51 to pivot about axle 52; this in turn causes the sliding action of the crankpin 54 in groove 53 which necessarily causes the rotation of the journals 47 and 48 in addition to the sliding movement. Consequently, as the journals move in translation and in rotation in the apertures 50, partition 38 and cutting blade 40 which are fixedly connected to the journals also move in translation and pivot about the moving pivot axis 55. The lateral immobilizing of blade support 46 is assured by plates 56 and 57 affixed exteriorly on the body of sleeve 18 as, for example, by means of screws. Partition 38, to which blade 40 is mounted, is made as thin as possible; preferably its thickness decreases progessively from journals 47 and 48 to its middle.

In the above construction, the cutting blade follows the movements of sliding piston 32 and pivots progressively around the movable axle in the direction of the movement of the piston.

FIG. 8 shows a yarn cutter equipped with a retractible plunger.

Yarn delivery tube 12 is extended by a retractible plunger, shown as a sliding tube 66, which may move in the direction of the transverse bore 22 when piston 32 has reached one of its extreme positions or at least is outside of the conduit 10. During this movement, the extremity of tube 66 meets with the yarn 16 and pushes it downwardly, which causes a deviation of the yarn and a reduction of the cutting angle, alpha. After the cutting, and in any case, before the movement of piston 32 in the opposite direction so as to effect a new cutting, tube 66 is brought back to its initial position (high position) in which it does not constitute a hindrance for the movement of blade 40. The movement of tube 66 may be controlled mechanically, for example, by means of a cam mounted in the same'manner as the small rod 51 FIG. 6 and 7 and acting upon a roller or cam follower integral with tube 66. The tube may be maintained against the cam by a spring or by a double lip groove on the cam. Tube 66 may also be controlled pneumatically, for example, by means of piston 32 acting as a distributing slidevalve, or through any appropriate means.

Of course, it is possible to combine the two embodiments according to FIGS. 5 and 8, as can be seen in FIG. 9; the control of the movements of blade 40 and tube 66 and their synchronization being effected through any suitable means; mechanical, pneumatic, electric, electromagnetic, etc.

Yarn cutters according to the above example were mounted on a device for air transport of yarn according to French patent application No. 72/ 19405 cited above, used for continuous rewinding. The control is effected by an electro-valve. The yarn cutters gave complete satisfaction for transportion speeds reaching up to 6,000 to 7,000 meters per minute.

The main advantage of the yarn cutter according to the present invention resides in the rapidity of the cutting, which prevents any possible accumulation of yarn at the time of the cutting and the risks of snags which it would entail.

Another advantage resides in its simplicity of construction and operation. Thus, the yarn cutter has only a small number of moving parts. The slide means can translate in both directions through the transverse opening of the sleeve, causing the cutting of the yarn once in each direction as the cutting means crosses the path of the yarn. The control of the yarn cutter is also highly simplified, which permits the easy integration of the cutting of the yarn into a series of completely automatic operations.

The present invention is applicable to the cutting of yarns of all types (continuous yarn or fiber yarn), of all natures (natural fibers, artificial or synthetic fibers) and of all counts.

Of course, the scope of the present invention is not limited to the embodiments described, but it may comprise numerous variations, for example, with respect to the cutting obstacle, the nature of its movement (translation, rotation, etc.), and the means to assure this movement.

What is claimed is:

1. Apparatus for cutting yarn transported continuously at high speeds by fluid under pressure through a conduit, the axis of which coincides with the normal path of travel of said yarn, comprising a yarn delivery tube and a yarn exit tube;

a sleeve having a central opening extending therethrough and a transverse opening perpendicular to said central opening, the end portions of said yarn delivery tube and said yarn exit tube coaxially aligned and carried in the upper and lower portions of said central opening, respectively;

cutting means carried within said transverse opening of said sleeve and adapted for transverse movement with respect to said normal path of said yarn, said cutting means including a cutting blade located in a plane parallel to said normal path of yarn; and

means to move said cutting means transversely between two positions located on either side of said normal path of said yarn whereby said cutting blade will be forced against and cut said'yarn each time it crosses the path of said yarn.

2. The apparatus of claim 1 wherein said cutting" means including said cutting blade has a cross-section in a plane perpendicular to the axis of said tubes which is small with respect to the cross-section of said tubes.

3. The apparatus of claim 2 wherein said means to move said cutting means includes slide means adapted to move within said transverse opening of said sleeve, said slide means including a piston having a lateral opening therethrough and said cutting means is carried in said lateral opening of said piston.

4. The apparatus of claim 3 further including pivoting means to pivotally rotate said cutting blade in the direction of and during the transverse movement of said cutting means and about a pivot axis which is perpendicular to the axis of said sleeve and to the axis of said transverse bore.

5. The apparatus of claim 4 wherein said pivoting means includes a support for said cutting means, said support carried by said piston during the transverse movement thereof; an axle fixedly mounted in the body of said sleeve; a rod hinged on said axle and pivotal thereabout; and means connecting said support to said rod whereby the transverse movement of said piston cause said support to rotate about said pivot axis.

6. The apparatus of claim 5 wherein said support includes two axially aligned journals housed at least partially within a transverse opening in said piston, the axis of said journals coinciding with said pivot axis; elongated apertures in the walls of said sleeve through which said transverse bore extends; said journals moving within said elongated apertures to pivotally rotate said cutting blade.

7. The apparatus of claim 1 and further comprising a retractible plunger within said central opening of said sleeve and adapted to extend within said transverse bore to contact said yarn at least when said cutting means is at one of said two positions.

8. The apparatus of claim 7 wherein said retractible plunger includes a sliding tubular tip which extends said yarn delivery tube.

? Patent Z Io. 9g 2 9 38 Dated December 2, 1975 'l'nventor(s) AHTEMONT, ET

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Please insert priority information to read as follows:

June 26, 1972 France. .72/23 275 0 April 9, 1973 France. .73/12 986 Signed and Scaled this thirtieth D f March 1976 Q [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Q AIIesIing Officer (ummixsimu'r nfParenls and Trademarks December 2, 1975 Patent.

HAUTEMONT ET AL.

lnventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent a":

e hereby corrected as shown below:

Please insert priority information to read as follows June 26, 1972 France. .72/23 275 April 9, 1973 France. .73/12 986 Signed and Sealed this thirtieth D f March 1976 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parents and Trademarks 

1. Apparatus for cutting yarn transported continuously at high speeds by fluid under pressure through a conduit, the axis of which coincides with the normal path of travel of said yarn, comprising a yarn delivery tube and a yarn exit tube; a sleeve having a central opening extending therethrough and a transverse opening perpendicular to said central opening, the end portions of said yarn delivery tube and said yarn exit tube coaxially aligned and carried in the upper and lower portions of said central opening, respectively; cutting means carried within said transverse opening of said sleeve and adapted for transverse movement with respect to said normal path of said yarn, said cutting means including a cutting blade located in a plane parallel to said normal path of yarn; and means to move said cutting means transversely between Two positions located on either side of said normal path of said yarn whereby said cutting blade will be forced against and cut said yarn each time it crosses the path of said yarn.
 2. The apparatus of claim 1 wherein said cutting means including said cutting blade has a cross-section in a plane perpendicular to the axis of said tubes which is small with respect to the cross-section of said tubes.
 3. The apparatus of claim 2 wherein said means to move said cutting means includes slide means adapted to move within said transverse opening of said sleeve, said slide means including a piston having a lateral opening therethrough and said cutting means is carried in said lateral opening of said piston.
 4. The apparatus of claim 3 further including pivoting means to pivotally rotate said cutting blade in the direction of and during the transverse movement of said cutting means and about a pivot axis which is perpendicular to the axis of said sleeve and to the axis of said transverse bore.
 5. The apparatus of claim 4 wherein said pivoting means includes a support for said cutting means, said support carried by said piston during the transverse movement thereof; an axle fixedly mounted in the body of said sleeve; a rod hinged on said axle and pivotal thereabout; and means connecting said support to said rod whereby the transverse movement of said piston cause said support to rotate about said pivot axis.
 6. The apparatus of claim 5 wherein said support includes two axially aligned journals housed at least partially within a transverse opening in said piston, the axis of said journals coinciding with said pivot axis; elongated apertures in the walls of said sleeve through which said transverse bore extends; said journals moving within said elongated apertures to pivotally rotate said cutting blade.
 7. The apparatus of claim 1 and further comprising a retractible plunger within said central opening of said sleeve and adapted to extend within said transverse bore to contact said yarn at least when said cutting means is at one of said two positions.
 8. The apparatus of claim 7 wherein said retractible plunger includes a sliding tubular tip which extends said yarn delivery tube. 